VanHalenLover:No, they can't - this reason alone is why I am very much against any kind of a reward/punishment system for quitting. There is simply no way to know the true reason for a disconnect, and thus, no fair way to implement a reward/punishment system
Acutally if we focus on the "reward" rather than the "punishment" it won't matter if WGT can't tell who has quit a game deliberately from those who just crash.
If you have set up a sufficient encouragement for people to continue then the important point is that they will be trying to complete their games, particularly if the reward is perceived as being higher than the reward to quit. (It seems that keeping your average low is seen as a reward by many people for quitting games that they have had a few bad shots in.)
If the game crashes one will think "Oh damn, I won't get those finishing credits, oh well... best start another game". (Which is better than the current situation when you find that everyone has quit on you and you are thinking "You lousy f***ers, all I wanted to do was finish a game in good company and I got teamed up with spineless idiots, I'm too mad to bother starting another game I think I'll go watch TV.")
So, whether the reward is credits or experience points or something we haven't thought of yet, the important thing is to make it more attractive to finish (if you can finish) than to quit.
Cheers
Gregg